The impact of shadow education on student academic achievement: Why the research is inconclusive and what can be done about it

Recent decades have brought global expansion of private supplementary tutoring, widely known as shadow education. Such tutoring consumes considerable resources and is usually viewed by participating households as an investment that will increase the recipients’ academic achievements. However, research on the effectiveness of tutoring has delivered inconclusive and even contradictory findings. Part of the reason lies in definitions and foci of research, since private supplementary tutoring may have many different formats, delivery mechanisms and intensities. As with other types of education, it is important also to investigate the qualities of the instructors and the motivations of the students. This creates a complex research arena, in which practical challenges arise from shortcomings in the instruments for securing data and limitations in methods for analyzing the data. This paper assesses the current state of the literature and makes recommendations for the future research agenda.